It is known to endow fiber materials such as woven fabrics for example with flame-retardant properties by treating them with certain liquid compositions. A number of known compositions of this type contain phosphorus compounds. This is apparent inter alia from U.S. Pat. No. 3,374,292, DE-A 25 09 592 and also from the abstracts of JP 2004-225 175 A2 and JP 2004-225 176 A2 in Chemical Abstracts (AN 141:175439 CA and AN 141:175 440 CA).
Also deserving of mention in connection with flame-retardant compositions are WO 2004/060990 A2 and the Derwent publication with AN 2006-806707 (concerning JP 2006/299 486 A), WO 00/11085 A and WO 99/67326 A.
Treating fiber materials for the purpose of rendering them flame retardant can be done, as will be known, by following various methods. In some cases, the flame-retardant composition can be applied by spraying. However, there are limits to spraying because the sprayability of possible components may be an issue and because of possible risks to the people doing the spraying.
A more frequently employed method is that of bath-impregnating the fiber materials by means of a padding process. In a padding process, however, only some of the flame retardant present in the padding liquor will end up on the fiber material, and this may lead to appreciable losses of costly products.
The exhaust method is very largely or completely free of the aforementioned disadvantage of the padding process. In the exhaust method, the fiber materials are treated with aqueous liquors that contain active substances such as flame retardants for example, and the fiber materials absorb these active substances quantitatively or almost quantitatively, so that the liquor depletes in these active substances in the course of its application. The numerous known processes for producing various grades of flame resistance on synthetic or blend fabrics have various disadvantages, of which the lack of durability to washing is mentioned most frequently. The currently best-known processes consist of a surface treatment which is subsequently subjected to thermosoling at 180° C. to 210° C. The cyclic phosphonates frequently employed for this purpose are readily water-soluble before fixing and are not durable to washing without thermosoling. Polymeric flame retardants, however, which remain on the surface, usually lead to a harsher hand for the textile. In contrast to fixing on the fiber surface in dry heat or by means of high-temperature thermosoling, the flame retardants introduced into the fiber from a high-temperature liquor by the exhaust method can also be combined simultaneously with a dyeing in one operation. An example of an apparatus for such a treatment is known from U.S. Pat. No. 3,922,737. But even without a combination with dyeing, such a treatment yields significant advantages, for example a superior permanence without thermosoling.
However, the matter is that a composition is particularly useful for the exhaust process when it is in the form of an aqueous dispersion but this dispersion does not have high stability. In contrast, aqueous dispersions used for padding processes should have good stability in order that they may not separate into their constituents on prolonged storage.
Some prior art compositions are aqueous dispersions having good stability after prolonged storage times. Such dispersions are useful for padding processes, but only of limited effectiveness in exhaust processes, since limited dispersion stability leads to optimum results in padding processes.
Prior art compositions additionally have further disadvantages when used for flame-retardant finishing.
For instance, relatively large amounts of phosphorus compounds are frequently required for prior art compositions to achieve acceptable flame protection. This applies even when the fiber materials consist wholly or predominantly of polyester.